1. Field of the Invention
This invention lies in the field of electrolyte fluids and processes for their preparation and use.
2. State of the Art
Fluids designed to contact mammalian cells all have as a general characteristic an osmotic pressure above about 260 milliosmoles/liter (mOs/L). The most common fluid given is 5% dextrose in H.sub.2 O. The second most common fluid given is normal saline (0.9N or 0.095% NaCl). It has been known (Black DAK, Lancet i: 305-312, 1954) that giving to adult humans much over 500 ml of normal saline per day leads to hyperchloremic acidosis since normal plasma contains about 136-145 mEq/L (milliequivalents per liter) plasma Na.sup.+ and about 100-106 mEq/L plasma of Cl.sup.- for an average Na:Cl milliequivalent ratio of about 1:36. There has been a long standing interest in creating an artificial plasma which dates back to 1883 with the origin of S. Ringer's solutions (J Physiol 4: 29-42, 1883) which are still in use today. It is now recognized that plasma is an "unmakable" solution since the law of electrical neutrality requires that the number of positive ions (cations) equal the number of negative ions (anions). Plasma itself has an exceedingly complex composition.
As any practicing clinician knows, since plasma contains 25-28 mEq/L of HCO.sub.3.sup.-, the number of measurable (.sup.+) cations in plasma is greater than the number of measurable (.sup.-) anions (mainly Cl.sup.-, HCO.sub.3.sup.-, and small amounts of Pi.sup.-1.8) in plasma by about 10-17 mEq/L plasma. The difference between cations and anions is called the apparent "anion gap". Efforts to cure the anion gap have been attempted since about the time of Ringer. A similar gap exists in each of extracellular and intracellular fluids.
The anion gap is now known to be caused mainly by the presence of polyanionic proteins, especially albumin which in man and mammals generally is a protein of about 68,000 M.W. (molecular weight) and which has about 20 negative (anion) charges/mole at the physiological pH of blood which is about 7.35 to 7.45 (see Tanford C. J Am Chem Soc 42: 441-451, 1950). Since the normal albumin concentration in, for example, mammalian blood is about 0.65 mM/L (millimoles per liter), about 13 mEq/L of the plasma anion gap is due to this source. Although albumin is found in all mammalian plasma, its chemical structure differs from species to species. If albumin from an animal such as the cow is intravenously introduced into man, an allergenic response promptly results. Therefore, only albumin specific to a species may be used repeatedly in a therapeutic situation. Although (suitably purified) albumin from one human can be so introduced into another without an allergenic response, human albumin is costly, a potential source of infection with viral agents, such as hepatitis or AIDS, and is difficult to obtain in quantity at the present time, as for therapeutic purposes. Thus, electrolyte solutions for therapeutic use which do not require use of a material such as albumin are still useful.
The history of electrolyte solutions including dialysis media can be briefly related:
(1) Sodium chloride. The earliest solutions used in medical therapy (Latta T. Lancet i: 274-277, 1832) contained sodium cations (Na.sup.+) and chloride anions (Cl.sup.-). Today, normal saline, which is isomolar NaCl (0.9-0.95%) is still given to patients intravenously. The problems with such solution are that it does not regulate pH and it induces hyperchloremic acidosis when given at much over 1 L/70 kg man/day.
(2) Ringer's. The second attempt to make a fluid which was not immediately lethal for contacting human cells was designed by S. Ringer in the 1880's and is still in use today. This fluid composition is essentially 130-145 mEq/L Na.sup.+, 2-4 mEq/L K.sub.+, 3.00 mEq/L Ca.sup.2+, 100-134 mEq/L Cl.sup.-, 7-14 mEq/L P.sub.i.sup.-1.8, and optionally up to 30-45 mEq/dl-Lactate or acetate, when a normal Na:Cl ratio is to be obtained.
Ringer's lactate is now known to cause profound difficulties with the cellular redox state (see equation 4) and has poor buffering capacity. This led in the 1920's and 30's to development of a series of physiologically compatible fluids designed by the great names of modern biology: Warburg, Locke, and Tyrode, and culminated in 1932 with the development of Krebs-Henseleit solution.
(3) Krebs-Henseleit. (Krebs HA, Henseleit KA. Hoppe-Seyler's Z Physiol Chem 210: 33-66, 1932) Krebs-Henseleit solution has a composition as given in Table 2 herein, the essential advance being that it normalizes the HCO.sub.3.sup.- /CO.sub.2 ratio, thus achieving adequate pH control. The value of this fluid is attested to by the fact that from it, or its partner, the Krebs Phosphate-Ringers (Krebs HA. Hoppe-Seyler's Z Physiol Chem 217: 193 1933), have evolved all the first modern renal dialysis fluids, and many special fluids for tissue perfusion or incubation.
The problem with Krebs-Henseleit solution, aside from too high Ca.sub.2.sup.+ (See Burritt MF, Pierides AM, Offord KP Mayo Clin Proc 55: 606-613, 1980) and Mg.sub.2.sup.+ by factors of about 2, and SO4.sub.2.sup.- by even more, is that the remaining anion gap was made up by Krebs with Cl.sup.-. Thus again, normal Cl.sup.- is 100-106 mEq/L in plasma, but Krebs-Henseleit contains 127.8 mEq/L. Krebs realized this deficiency and attempted (Krebs HA. Biochem Biophys Acta 4: 249-269.1950) to remedy this problem with the creation of Krebs Serum substitute (see Table 2). Because he failed to understand from a theoretical point of view how such a problem could be solved, he picked anions on the basis of O.sub.2 consumption measurement in tissue slices. The anions picked to make up the 13 mEq/L anion gap were glutamate.sup.-, fumarate.sup.2-, and pyruvate.sup.-, which are inappropriate in living cells (although not in tissue slices where cut surfaces of cells are exposed) because glutamate.sup.- and fumarate.sup.- cannot readily penetrate the cell membrane.
This was really how matters stood until the development of widespread renal dialysis in the 1960's. The pioneering of these life saving techniques largely by Scribner in Seattle, Scribner in Washington, and Merrill and his group at Harvard led to the need for a cheap, convenient fluid. Krebs-Henseleit solution (with only very slight variations, see Table 2) was used by the Harvard group in open baths where the necessary CO.sub.2 was lost to the atmosphere with a resultant rise in pH (see equation 1) and the conversion of HCO.sub.3.sup.- to CO.sub.3.sup.2- salts. This simple problem was inconvenient to the physicians in charge and led them, well-meaning but misguidedly, to seek a more convenient substitute for Krebs-Henseleit solution.
(4) Gilman-Mudge-Scribner and the Substitution of Acetate for HCO.sub.3 in High-Volume Fluids. Alfred Gilman of Columbia University was, in effect, the dean of American pharmacologists, and he and his students in the middle 1940's reasoned that acetate is ultimately metabolized to CO.sub.2, and since it readily penetrated cell walls, it could be used as an alternative source of HCO.sub.3.sup.- (Mudge G H, Manning J A, Gilman A. Proc Soc Exptl Biol Med 71: 136-138, 1949). While all of this is true, it ignores the profound upsets in mineral and energy metabolism which, at the time, no one recognized, but which are now clear and which have led to the present invention, since it is now absolutely clear that acetate containing fluids causes profound toxicity which can easily be overcome and therefore can no longer be tolerated in view of the new art described here.
About 80% of all current hemodialysis fluids in the U. K. use 35 mM/l acetate.sup.- in combination with 130-150 mM Na.sup.+, 1-1.75/mmole Ca.sup.2+, 0-1mM/L Mg.sup.2+, and 100/mM/L Cl.sup.- (See Parsons F M, Stewart W K In: Drukker W, Parsons F M, Maher J F, eds. Replacement of Renal Function by dialysis. 2nd Edition, 1984, Martinus Nijhoff: Hingham, pp 148-170). Minor alterations in commercial fluids involve the use of d,l-lactate (35-50 mM/L) in place of acetate, but this alternative from commercial sources is almost as unsatisfactory as acetate and is submitted to be no longer tolerable for patient care.
Prior art illustrative of electrolyte solutions are provided in Tables I, II, and III herewith.
TABLE I __________________________________________________________________________ Prior Art Fluids to Which Macromolecules Have Been Added (1) (6) Normal 5% (2) Range Plasma Dextrose Normal (3) (4) (5) of Units N.E.J.M. in Saline Ringer's Lactated Acetated Peritoneal mmoles 283, 1285 Water 0.9% Injectable Ringer's Ringer's Dialysis __________________________________________________________________________ L fluid 1970 (Commercial) Na 136-145 154 147 130 140 131-141.5 K 3.5-5.0 4 4 10 0-4 Ca 2.1-2.6 2.5 1.5 2.5 1.75-2.0 free [Ca2+] [1.06] Mg 0.75-1.25 2.5 1.5 1.5 0.25-0.75 free [Mg2+] [0.53] .SIGMA. mEq Cations 142.7-153.2 154 156 137 158 135-151 Cl 100-106 154 156 109 103 96-106 HCO.sub.3 26-28 .SIGMA. Pi 1-1.45 SO.sub.4 0.32-0.94 L-lactate 0.6-1.8 28(d,1) 8(d,1) 35-45(d,1) pyruvate Lact/pyr * * * D-.beta.-OHbutyrate acetoacetate .beta.-HB/ acac acetate 47 45 Other .SIGMA.mEq anions 128.7-139.4 154 156 137 158 135-151 Na/Cl 1.28-1.45 1.00 0.94 1.19 1.36 1.36-1.33 Glucose 3.9-5.6 278 83-236 or others CO.sub.2 0.99-1.39 pH 7.35-7.45 .apprxeq.5.5-6.5 .apprxeq.5.5-6.5 .apprxeq.6.0-6.5 .apprxeq.6.0-6.5 .apprxeq.6.0-6.5 .apprxeq.6.0-6.5 .SIGMA. mOsm 285-295 278 310 309 272 312 347-535 Use: Hydration NaCl Multiple IV Fluid Electro- Peritoneal & Nutrition Replace- Blood lyte Dialysis ment Products Replace- Administration ment __________________________________________________________________________ (1) Facts and Comparisons Lippincott, St Louis, 1981 (2) Facts and Comparisons Lippincott, St Louis, 1981 (3) Facts and Comparisons pp 35d-53, Oct '81-Aug '83, JB Lippincott, St Louis. Ringer S. J Physiol 4: 29-42, 1883. (4) Facts and Comparisons pp 35d-53, Oct '81-Aug '83, JB Lippincott, St Louis. Hartmann AF. J Am Med Assoc 103: 1349-1354. 1934. (5) Facts and Comparisons pp 35d-53, Oct '81-Aug '83, JB Lippincott, St Louis. Fox CL, Winfield JM, Slobody LB, Swindler CM, Lattimer JK. J Am Me Assoc 148: 827-833, 1952. (6) Facts and Comparisons pp 35d-53, Oct '81-Aug '83, JB Lippincott, St Louis.
TABLE II __________________________________________________________________________ Fluids to Which Complex Macromolecules Are Added (8) (13) Normal Hyper- Range Plasma tonic (10) (11) (12) of Units N.E.J.M. NaCl (9) Krebs Brigham Scribner's Acetate mmoles 283, 1285 (Resusitation) Tyrode's Henseleit Dialysis Dialysis Hemodialysis __________________________________________________________________________ L fluid 1970 Na 136-145 1200 150.1 143 140 135 130-145 K 3.5-5.0 5.9 5.9 4 1.5 0-5 Ca 2.1-2.6 1.8 2.5 1.25 1.25 1.25-2.0 free [Ca2+] [1.06] Mg 0.75-1.25 0.45 1.2 0.5 0.5 0-1 free [Mg2+] [0.53] .SIGMA.mEq Cations 142.7-153.2 1200 160.5 156.3 147.5 140 138-147 Cl 100-106 1200 147.48 127.8 120.7 105 92-111 HCO.sub.3 26-28 11.9 25 26.8 .SIGMA. Pi 1-1.45 1.22 1.18 SO.sub.4 0.32-0.94 1.18 L-lactate 0.6-1.8 pyruvate Lact/pyr D-.beta.-OHbutyrate acetoacetate .beta.-HB/ acac acetate 35 35-45 Other .SIGMA.mEq anions 128.7-139.4 1200 161.6 157.3 147.5 140 138-147 Na/Cl 1.28-1.45 1.00 0.96 1.12 1.16 1.29 1.29-1.31 Glucose 3.9-5.6 5.6 10 or others CO.sub.2 0.99-1.39 -- 1.24 1.24 pH 7.35-7.45 .apprxeq.5.5-6.5 7.1 7.4 7.4 .apprxeq.5.5-6.5 .apprxeq.5.5-6.5 .SIGMA. mOsm 285-295 2400 318.8 308 304.8 278.2 258-309 Use: Hemorrhage Perfusion General Hemo- Hemo- Hemo- & Shock dialysis dialysis dialysis __________________________________________________________________________ (8) Velasco IT, Pontieri V, Rocha M, Silva E, Lopes OU. Am J Physiol 239: H664-673, 1980. Hypertonic Ringer's Lactate has also been advocated in treatment of hemorrhage. See Nerlich M, Gunther R, Demling RH. Circ Shock 10:179-188, 1983. Both a re inadequate. (9) Tyrode MJ. Arch int Pharmacodyn 20: 205, 1910. (10) Krebs HA, Henseleit KA. HoppeSeyler's Z Physiol Chem 210: 33-66, 1932. (11) Murphy WP, Swan RC, Walter C, Weller JM, Merrill JP. J Lab Clin Med 40: 436-445, 1952. (12) Mion CM, Hegstrom RM, Boen ST, Scribner BH. Trans Am Soc Artif Inter Organs 10: 110-113, 1964. The use of acetate in physiological fluids was first proposed by: Mudge GH, Manning JA, Gilman A. Proc Soc Exptl Biol Me 71: 136-138, 1949. (13) Parsons FM, Stewart WK. In: Replacement of Renal Function by Dialysi (Drukker W, Parsons FM, Maher JF, eds) 2nd Edition, Martinus Nijhoff, Hingham, pp 148-170.
TABLE III __________________________________________________________________________ " Prior Art" Fluids To Which Macromolecules Have Been Added (15) Normal Krebs (16) (17) (19) (20) Plasma Liver Perfusion with Schimassek Krebs (18) Bahlman Fulgraff Units N.E.J.M. Bovine serum Liver Kidney Hepatocyte Kidney Kidney mmoles 283, 1285 Albumin and Red Cells Perfusion Perfusion Incubation Perfusion Perfusion __________________________________________________________________________ L fluid 1970 Na 136-145 153 151.54 148 153 147 143 K 3.5-5.0 5.9 5.9 5.9 5.9 4.9 4.74 Ca 2.1-2.6 2.5 1.8 2.5 2.5 2.56 1.25 free [Ca2+] [1.06] Mg 0.75-1.25 1.2 0.49 1.2 1.2 1.2 0.59 free [Mg2+] [0.53] .SIGMA.mEq Cations 142.7-153.2 166.3 162.02 161.3 166.3 159.4 151.15 Cl 100-106 127.8 147.48 127.8 127.8 127 113.04 HCO.sub.3 26-28 25 11.9 25 25 24.5 25 .SIGMA. Pi 1-1.45 1.18 1.22 1.18 1.18 1.18 1.18 SO.sub.4 0.32-0.94 1.18 -- 1.2 1.2 1.18 1.18 L-lactate 0.6-1.8 (10 Na-1 Lac) 1.33 5 Na 1-Lac 9.09 2.75(d,1) 3.5(?d,1) pyruvate 0.09 0.91 0.25 0.25 Lact/pyr 14.8 10 10 7 or 14 D-.beta.-OHbutyrate acetoacetate .beta.-HB/ acac acetate 5.0 Other .SIGMA.mEq anions 128.7-139.4 167.0 162.81 162.3 167.0 159.1 151.31 Na/Cl 1.28-1.45 1.12 1.03 1.16 1.20 1.20 1.26 (1.20) Glucose 3.9-5.6 5.45 6.2 -- or others 6.7 urea 6.7 urea CO.sub.2 0.99-1.39 1.25 1.24 1.24 1.24 1.24 1.24 pH 7.35-7.45 7.4 7.1 7.4 7.4 7.4 7.4 .SIGMA. mOsm 285-295 328 321 318 328 327 307.9 Albumin (g %) 3.5-5 3.9 2.5 5 2.5 5.5 0.05 __________________________________________________________________________ *Artificial perfusion fluid generally add 1.5 to 8 g % albumin, dialyzed against a medium listed in Table I; that is KrebsHenseleit (10), KrebsRinger Phosphate (11), Tyrode's (9), Locke's (8), or KrebsHenseleit with a lowered Ca.sup.2+ t o the 1 mM range, particularly in heart perfusion. They may or may not contain red cells. KrebsHenseleit is known to contain about twice the amount of ionized CA.sup.2+ as serum. (15) Hems R, Ross BD, Berry MN, Krebs HA. Biochem J 101, 284, 1966; Krebs Henseleit (10) with 3.9 g % bovine albumin. (16) Schmassek J. Biochem Z 336, 460, 1963. Essentially Tyrode's (9) with added lactate and pyruvate. (17) NishiitsutsujiUwo JM, Ross BD, Krebs HA. Biochem J 103, 852-862, 1967; KrebsHenseleit (10) with 5 g % albumin, dry. (18) Crow KE, Cornell NW, Veech RL. Biochem J 172, 29-36, 1978, KrebsHenseleit (10) with 2.5 g % dialysed albumin plus llactate plus pyruvate. (19) Bahlman J et al. Am J Physiol 212, 77 1967; Krebs Henseleilt (10) with lactate and pyruvate and 5.5 g % bovine albumin (20) Fulgraff et al. Arch int Pharmacodyn 172, 49, 1972; KrebsHenseleit (10) with 1/2 Mg and Ca plus lactate and pyruvate plus 5 mM acetate, plus 0.05 g % albumin plus 2 g % albumin plus 2 g % hemocel.
Prior art electrolyte solutions which incorporated albumin are illustrated in Table III herewith. In the prior art solutions, even those containing albumin, the sodium cation to chloride anion milliequivalent ratio was never normalized or made to fall in a range associated with normal animal cells in a manner which would not induce measureable toxic effects in the cells so contacted (or with the particular animal fluid which was to be mimicked by a particular fluid, for example, human blood plasma compared to Krebs-Henseleit solution).
So far as now known, the only organic polyanionic substance heretofore employed in aqueous electrolyte solutions has been albumin, "hemocel" or gelatin and no such electrolyte solution is believed to have either a Na:Cl milliequivalent ratio in the physiologically normal range or an electrolyte composition comparable to normal mammalian (or human) blood plasma. Furthermore, so far as is now known, no albumin containing such electrolyte solution has ever previously been employed in in vivo mammalian therapy (e.g., parenterally, intravenously, or otherwise administered).
In even the field of plasma expanders (which is regarded as an application for aqueous electrolyte solutions suitable for contacting living animal cells), it has heretofore been thought by those skilled in the art (see, for example, Mudge on "Agents Affecting Volume and Composition of Body Fluids", pp. 848-884 of Goodman & Gilman's, The Pharmacologic Basis of Therapeutics published in 1980 by Macmillan, New York, that an ideal plasma expander should be, among other properties, pharmacologically inert. While many substances have been investigated as plasma expanders, organic polyanionic substances (whether natural or synthetic in origin) do not appear to have previously been considered. Dextran (see Mudge, reference cited) appears to be regarded as the best known artificial plasma expander, yet dextran is a branched polysaccharide of about 200,000 glucose units with a molecular weight of about 40 million and which has no anionic charge.
In my copending U.S. patent applications U.S. Ser. No. 623510, U.S. Ser. No. 623102 and U.S. Ser. No. 623443, identified by attorney's docket numbers P-83,2198, P-83,2213, P-83,1655 and P-85,1402, P-85,1403, P-85,1404 provide aqueous electrolyte fluids which are also useful for contacting living animal cells, but these electrolyte fluids do not, in contrast to the fluids of the present invention, require the use of organic polyionic substances. For present disclosure purposes, the entire disclosure and contents of these copending applications is incorporated herein by reference. Definitions used in such copending applications, for example, are incorporated hereinto by reference.